1. Field of the Invention
The present invention relates to an oil relief valve, and more particularly, to an oil relief valve capable of reducing an oil pressure shock, increasing a relief valve opening speed, and reducing an oil pressure trembling phenomenon.
2. Description of Related Art
Generally, a fluid such as oil needs to be supplied to apparatuses such as an engine, a transmission, and the like, of a vehicle at a predetermined pressure. For this purpose, there is a need to drive a pump such as an oil pump. In this case, a pressure of a discharged fluid is changed according to the driving of the pump. The oil pump shows a linear increase in a flux as an engine RPM increases. The increase in a flow rate causes pressure to rise within an engine oil circuit and when an engine pressure is higher than necessary, a problem of oil leakage may occur due to an increase in internal pressure of an oil sealing part and power loss may be increased at the time of the rotation of the oil pump.
In order to prevent the above problems, as illustrated in FIG. 1, an oil pump housing 100 is provided with a relief valve 1. The relief valve 1 includes a plunger 20 that slidably moves vertically in a valve hole 10, a spring 30 that elastically supports the plunger 20, and a support 40 that supports the spring 30. When an oil pressure is above a set pressure, the relief valve 1 interconnects an oil passage 60 with a relief passage 50 to discharge oil through a bypass flow that returns oil to an oil fan again. Therefore, there is a need to appropriately maintain an oil discharge pressure of the oil pump at an appropriate level and prevent damage due to a high pressure. That is, the relief valve 1 is directly received with an oil pressure of oil that is pumped and discharged from the oil pump and when an oil pressure is largely increased, the plunger 20 moves downwardly while the spring 30 is compressed. As the plunger 20 moves downwardly, the oil passage 60 and the relief passage 50 are interconnected with each other such that a part of oil is introduced into the relief passage 50.
According to the relief valve 1 of the related art, the flux of oil that is introduced and returns to the relief passage 50 is linearly controlled by an oil pressure and a spring 30 constant within the relief valve 1. Therefore, as illustrated in FIG. 2, an oil pressure trembling phenomenon excessively occurs on the way to the opening and closing of the oil relief valve 1, such that an operation of the relief valve 1 controlled depending on the oil pressure may be instable and a response speed may be slow until the relief valve 1 becomes a full open state, that is, the operation of the relief valve 1 reaches a normal state. Further, the speed of the relief valve 1 is slow immediately after the relief valve 1 starts to open under the condition that oil viscosity is low, such as cold starting during winter season and thus, a large oil pressure is still generated, causing the oil pressure shock to be large. Therefore, a sealing part may be damaged and power loss may occur.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.